fix(approvals,l10n,theme): usertest findings — localized prompts, no-data confirm, .chain log path, honest wording, AA contrast

- approvals: empty/legacy hub prompts render the localized fallback;
  approving without show: data asks for conscious confirmation first
- chain_log: write to ~/.chain/logs/studio-errors.log (was .fai),
  one-time best-effort migration of the legacy file + rotation sibling
- l10n: 'manipulationssicher' -> 'manipulationserkennend', neutral
  WORM-1 blurb, doctor pill 'Integritätskette v1', federation hint
  says the CA authenticates the first connect (DE+EN)
- theme: muted text token now >=4.5:1 on canvas, cards and elevated
  dark surfaces (was 3.7:1 on cards)

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/l10n/app_localizations_en.dart

@@ -150,7 +150,7 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get welcomeDocAuditBlurb =>
-      'How the hash chain works and why WORM-1 is enough for KRITIS.';
+      'How the hash chain makes later edits detectable — and what integrity level WORM-1 does (and does not) provide.';
 
   @override
   String get welcomeDocFlowsTitle => 'Flow composition';
@@ -1882,6 +1882,16 @@ class AppLocalizationsEn extends AppLocalizations {
   String get approvalsNoPayload =>
       'No data was attached for review. The flow\'s approval step chooses what to show via its \"show:\" field — set it to surface the data behind this decision.';
 
+  @override
+  String get approvalsNoDataConfirmTitle => 'Approve without review data?';
+
+  @override
+  String get approvalsNoDataConfirmBody =>
+      'This flow deliberately attached no review data (no \"show:\" on its approval step). You can still approve — but you would be deciding without seeing the data behind this decision.';
+
+  @override
+  String get approvalsNoDataConfirmAction => 'Approve anyway';
+
   @override
   String get approvalsRequestFallback => 'Approval required for this step';
 
@@ -2052,7 +2062,7 @@ class AppLocalizationsEn extends AppLocalizations {
   }
 
   @override
-  String get doctorChainPillOk => 'WORM-1';
+  String get doctorChainPillOk => 'Integrity chain v1';
 
   @override
   String get doctorChainPillTamper => 'TAMPER';
@@ -2863,5 +2873,5 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get federationEnrollmentHint =>
-      'Hand the token to the satellite operator over a secure channel. The bundled CA makes the satellite\'s first connect tamper-proof.';
+      'Hand the token to the satellite operator over a secure channel. The bundled CA authenticates the satellite\'s first connect.';
 }